JP6612868B2 - Load side voltage detection for utility meters - Google Patents

Description

  The present disclosure relates to the field of utility meters, and more particularly to an electric meter having a three-phase service switch.

  A utility meter is a device that measures the consumption of goods of utility companies such as electric power, gas, water, etc., particularly by facilities such as houses, factories, or commercial facilities. Utility service providers (public resource service providers) employ utility meters in order to track the usage of products of utilities by consumers for reasons such as billing and product demand forecasts.

  An electric meter is a type of utility meter that is configured to measure an amount related to the consumption of electrical energy by a facility or other electrical equipment. Typically, power companies allow electrical equipment to have continuous access to electrical energy. However, in some cases, such as when the customer is delinquent, the power company may determine that it is necessary to prevent the customer's electrical equipment from accessing electrical energy. For this reason, some electric meters are provided with a service switch that can be set via a utility meter so as to supply electric power to an electric device in the closed state and to block access to the electric power in the open state. Depending on the model, the service switch can be remotely controlled and the technician can supply or shut off electrical energy via the electric meter without setting up the electric meter in the field.

  After sending a remote signal to the electrical meter service switch, the utility service provider typically cannot determine whether the service switch has successfully entered the desired operating state. If the service switch does not enter the desired operating state, the electricity meter will either (i) prevent the paying customer from accessing the electrical energy, or (ii) if the customer does not want to access the electrical energy Can be able to.

  Thus, there remains a need to improve the performance of utility meters so that utility service providers can accurately and reliably determine the operating state of service switches for other types of utility meters that include electrical meters and service switches.

  According to an exemplary embodiment of the present disclosure, an apparatus used in a utility meter includes at least one line path, a service switch, and a monitoring unit. The at least one circuit path connects electrical energy to a load. The service switch is operatively connected to the at least one line path; (i) an open state in which an open circuit is formed in the at least one line path; and (ii) a closed circuit in the at least one line path. Can be set to the closed state in which is formed. The monitoring unit is operatively connected to the at least one line path between the load and the service switch, and is configured to detect the presence or absence of a line voltage at the load. The monitoring unit further generates (i) an open circuit signal in response to detecting the absence of a line voltage in the load, and (ii) a closed circuit in response to detecting the presence of a line voltage in the load. It is configured to generate a signal.

  In accordance with another exemplary embodiment of the present disclosure, a method of operating a utility meter includes providing an open circuit in at least one circuit path that connects electrical energy to a load at a service switch, thereby providing the load as described above. The load is connected to the electrical energy by disconnecting from the electrical energy and forming a closed circuit in the at least one line path with the service switch. The method further detects the presence or absence of a line voltage at the load, generates an open circuit signal in response to detecting the absence of the line voltage at the load, and detects the presence of the line voltage at the load. In response, a closed circuit signal is generated.

  These as well as other features and advantages will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and the accompanying drawings.

FIG. 1 is a block diagram of an example of a metering system that includes a utility meter including a service switch and a monitoring unit configured to determine an operating state of the service switch.

FIG. 2 is a block diagram showing a structure of an example of a monitoring unit of the utility meter in FIG.

FIG. 3 is a schematic diagram showing in more detail the structure of an example of the monitoring unit of the utility meter of FIG.

FIG. 4 is a signal timing diagram of signals associated with the metering system of FIG. 1 and is a signal timing diagram when the service switch is in a closed state and an open state.

FIG. 5 is a flowchart showing an example of an operation method of the metering system of FIG.

  To facilitate an understanding of the principles of the present disclosure, embodiments described by the drawings and the following specification are set forth. Needless to say, this is not intended to limit the scope of the present disclosure. The disclosure also includes all modifications and variations to the illustrated embodiments, as well as further applications of the principles of the disclosure, as would normally occur to one of ordinary skill in the areas related to the disclosure. Needless to say.

  As shown in FIG. 1, the metering system 100 is electrically connected to a power source 104 and an electrical load 112 via a power line 108 and an electrical load line 116. The power line 108 distributes power generated by the source 104 (also referred to herein as a utility service provider, power company, or utility) to the metering system 100. The electric load line 116 distributes the electric power that has passed through the metering system 100 to the load 112. Metering system 100 is configured to measure power consumption by load 112.

  In the exemplary embodiments described herein, a three-phase, four-wire electrical service is used, as is well known in the art. Therefore, power line 108 includes an A phase power line 108a, a B phase power line 108b, a C phase power line 108c, and a neutral line 108d. Similarly, load line 116 includes an A-phase load line 116a, a B-phase load line 116b, a C-phase load line 116c, and a neutral line 116d. As will be described in detail later, load lines 116a, 116b, 116c, and 116d are connected to corresponding power lines 108a, 108b, 108c, and 108d, respectively.

  The metering system 100 includes a mounting device 120 and a utility meter 124 mounted on the mounting device 120. In the exemplary configuration of FIG. 1, the mounting apparatus 120 includes three line side sockets 128 that are electrically connected to the source 104 via power lines 108a, 108b, and 108c, and load lines 116a, 116b, and 116c. And three load side sockets 132 electrically connected to the load 112. The mounting apparatus 120 includes a neutral wire socket 134 connected to the neutral wires 108d and 116d. Accordingly, load 112 is configured to receive three-phase power from source 104 via meter 124. The sockets 128, 132, and 134 are made of metal and configured to withstand high current and high voltage. In other embodiments, the mounting device 120 includes any suitable number of sockets 128, 132, 134 formed of any suitable material that will depend on the power demand of the load 112.

  The utility meter 124 includes a housing 136, at least one current coil 140, a voltage sensor 142, a current sensor 144, a service switch 172, a monitoring unit 192, and a measuring unit 152. In the present embodiment, the current coil 140 includes three current coils 140 a, 140 b, and 140 c corresponding to the A phase, the B phase, and the C phase of the electric source 104. The current coils 140a, 140b, 140c are at least partially disposed within the housing 136 and are conductors configured to provide electrical connection to the power lines 108a, 108b, 108c and the load lines 116a, 116b, 116c ( Example: copper conductor). Each current coil 140a, 140b, 140c connects a corresponding power line 108a, 108b, 108c to a respective load line 116a, 116b, 116c via a service switch 172. Each of the current coils 140 includes two blades 156 that are configured to extend partially from the housing 136. Blade 156 is configured to provide a reliable mechanical and electrical connection between current coil 140 and sockets 128, 132. The current coil 140 and the blade 156 may also mechanically support the meter 124 at a mounting position (shown in FIG. 1) on the mounting apparatus 120. As described above, each current coil 140 is configured to transmit any one of the A-phase, B-phase, and C-phase line voltage. Current coil 140 and power lines 108 and 116 are configured to define three line paths 146a, 146b and 146c for transferring power between source 104 and load 112.

  The voltage sensor 142 includes a circuit capable of generating or configured to measure voltage signals representing the voltages of the current coils 140a, 140b, 140c, respectively. Each voltage sensor 142 may appropriately include a voltage divider (not shown) connected to each current coil 140a, 140b, 140c. Such a voltage sensor 142 is conventionally known. The voltage sensor 142 is operably coupled to the analog to digital converter 148 of the measurement unit 152 to provide a voltage measurement signal to the measurement unit 152.

  The current sensor 144 is disposed in a relationship of detecting current with respect to the current coils 140a, 140b, and 140c. Current sensor 144 may be any conventional current sensor including a current transformer. The current sensor 144 is configured to generate a scaled-down version of the current passing through the current coils 140a, 140b, 140c. Each scaled-down current constitutes a current measurement signal. Therefore, in this embodiment, the current coils 140a, 140b, and 140c form a primary winding of a transformer that is formed together with the current sensor 144. The current sensor 144 is electrically connected to the analog / digital converter 148 in order to connect the current measurement signal to the measurement unit 152.

  The measurement unit 152 detects, measures, and determines one or more electric and / or electric energy consumption values based on the electric energy flowing between the sockets 128, 132, 134, thereby measuring data or consumption data. Any suitable circuit (s) configured to generate The measurement unit 152 includes an analog / digital (A / D) converter 148 and a processing circuit 150. A / D converter 148 is operably coupled to receive a voltage measurement signal from voltage sensor 142 and to receive a current measurement signal from current sensor 144. The analog-to-digital converter 148 is configured to generate a corresponding digital measurement signal that is processed by the processing circuit 150 to generate measurement data.

  With continued reference to FIG. 1, the utility meter 124 further includes a power source 170, a memory 180, a transceiver 184, and a display 188. The power supply 170 generates electrical outputs suitable for powering at least the analog to digital converter 148 and the processing circuitry 150, preferably the transceiver 184, the display 188, and the memory 180. The power source 170 is operably coupled to and generates power from at least one power line (108a in FIG. 1).

  The service switch 172 is shown as a three-phase service switch in the illustrated embodiment and is operably coupled to the line path 146 and the measurement unit 152 and is in a closed state (first operating state) and an open state (second (Operation state) can be set. In the closed state, the service switch 172 is configured to form a closed circuit in each of the line paths 146a, 146b, 146c. Each closed circuit allows power transfer from the source 104 to the load 112 via the power lines 108, 116 and the current coil 140. In a three-phase system, all three line voltages are applied to the load 112 when the three-phase service switch 172 is closed. In the open state, the service switch 172 is configured to form an open circuit in each of the line paths 146a, 146b, 146c. Each open circuit prevents power transfer from the source 104 to the load 112 via the power lines 108, 116 and the current coil 140. In a three phase system, the three line voltages are isolated from the load 112 when the three phase service switch 172 is open.

  Service switch 172 includes a relay or any other suitable device configured to controllably disconnect or reconnect power to load 112. In the illustrated embodiment, service switch 172 is shown configured to connect and disconnect three-phase power to load 112. Also, in some cases, service switch 172 includes a motor or solenoid that operates the contacts of the electromechanical switch between the open and closed states. In the example of the three-phase system of FIG. 1, service switch 172 may include three independent relays or other suitable devices. In particular, the measuring unit 152 can be appropriately configured to control the state of the service switch 172 based on the customer's payment status associated with the load 104 and the consumption level of the load. Service switch 172 is configured to simultaneously open or close all three phases to prevent damage to a three-phase load (load 112) such as a motor. Therefore, the service switch is not configured to perform individual line voltage control or individual phase control.

  The memory 180 is operatively coupled to the measurement unit 152 and configured to store measurement data generated by the measurement unit. In addition, the memory 180 is configured to store program data for operating the utility meter 124 in accordance with a method 500 (FIG. 5) described below and any other electronic data used or generated by the measurement unit 152. . In this specification, the memory 180 is also referred to as a non-transitory machine-readable recording medium.

  The transceiver 184 is operatively coupled to the measurement unit 152 and configured to transmit electrical data to the source 104 and / or an external unit (not shown) and receive electrical data from the source and / or external unit. The In one embodiment, the transceiver 184 is a radio frequency (“RF”) transceiver that transmits and receives RF signals. In another embodiment, the transceiver 184 includes an automatic meter reading (AMR) communication module configured to transmit data to the AMR network and / or other suitable devices. Further, the transceiver 184 can be configured to perform data communication via a wired or wireless connection via the Internet. In another embodiment, the transceiver 184 is configured to communicate with an external device or source 104 by any of a variety of means used in the art, such as power line communication, telephone line communication, or other communication means. .

  The display 188 is operably coupled to the measurement unit 152 and is configured to display data associated with the utility meter 124 in a visually comprehensible manner. For example, the display 188 may be configured to display the measurement data generated by the measurement unit 152 and the state of the service switch 172 determined by the monitoring unit 192. Display 188 is any desired display device, such as a liquid crystal display unit.

  A monitoring unit 192 shown as a three-phase monitoring unit is operatively connected to the measuring unit 152 and the line paths 146a, 146b, 146c. The monitoring unit 192 detects the presence or absence of a line voltage at the load 112, generates an open circuit signal (first output signal) in response to detection of the absence of the line voltage at the load 112, and detects the line voltage at the load 112. Is configured to generate a closed circuit signal (second output signal) in response to detecting the presence of. In order to facilitate detection of the presence or absence of a line voltage in the load 112, the monitoring unit 192 is configured so that the monitoring unit 192 is electrically connected to each phase of the load 112 even when the service switch 172 is in an open state. , Connected to the load side of service switch 172 (between service switch 172 and load 112). The monitoring unit 192 is configured to generate an open circuit signal only when all three phases of the three-phase service switch 172 are in the open state. The monitoring unit 192 is configured to generate a closed circuit signal only when all three phases of the three-phase service switch 172 are in the closed state.

  In the illustrated embodiment, the monitoring unit 192 includes two independent digital electrical output units 244 and 248 that are each configured to be connected to a corresponding digital input unit of the measurement unit 152. . The output units 244 and 248 transmit the closed circuit signal and the open circuit signal as digital signals (logic signals), respectively. In particular, the monitoring unit 192 is configured to generate a closed circuit signal as a digital high (logic “1”) at the output unit 244. When the monitoring unit 192 does not generate a closed circuit signal, the output unit 244 communicates a digital low (logic “0”). The monitoring unit 192 is also configured to generate an open circuit signal as digital low (logic “0”) at the output unit 248. When no open circuit signal is generated, output 248 communicates a digital high (logic “1”). Therefore, the measuring unit 152 is configured to finally determine the operating state of the service switch 172 by monitoring the digital outputs 244 and 248 of the monitoring unit 192.

  In the illustrated embodiment, the monitoring unit 192 detects three analog signals representing the load-side AC voltage, and “successfully opened”, “successfully closed”, as described in more detail later. Digital control signals representing “unsuccessful open state” and “unsuccessful closed state” are generated. Therefore, the monitoring unit 192 releases the processing unit 150 from the load of sampling the analog signal and determining the state of the three-phase service switch 172.

  As shown in FIG. 2, the exemplary embodiment of the monitoring unit 192 includes three voltage dividers 218a, 218b, 218c, three crossing detection circuits 220a, 220b, 220c, and three peak detectors 224a, 224b, 224c. And a logical AND circuit 228 and a logical OR circuit 232.

  Voltage divider 218a includes a voltage output unit 219a that is operatively connected to A-phase line voltage line path 146a and transmits divided voltage signal Av. Voltage divider 218b is operably connected to B-phase line voltage line path 146b and includes a voltage output unit 219b that transmits divided voltage signal Bv. Similarly, voltage divider 218c includes a voltage output unit 219c that is operatively coupled to C-phase line voltage line path 146c and transmits divided voltage signal Cv. The voltage dividers 218a, 218b, 218c are each configured to convert the line voltage level (or voltage indication of the line voltage) into a low voltage or reduced line signal. Each reduced line signal is superimposed on a DC voltage (DC bias voltage) of a predetermined magnitude to form a divided voltage signal Av, Bv, Cv, as will be described in further detail below. The voltage divider 218a is operatively connected to supply a divided voltage signal Av to the cross detection circuit 220a, and the voltage divider 218b is operably connected to supply a divided voltage signal Bv to the cross detection circuit 220b. The voltage divider 218c is operatively connected to provide a divided voltage signal Cv to the crossing detection circuit 220c. Needless to say, in some embodiments, the voltage dividers 218a, 218b, 218c may be used as the voltage sensor 142 of FIG.

  Referring to FIG. 2 again, the intersection detection circuit 220a includes a pulse output unit 236a that transmits a pulse signal Ap (also referred to as a rectangular waveform). The cross detection circuit 220a compares the voltage representing the divided voltage signal Av with the reference voltage signal, and generates a pulse of the pulse output 236a in response to the signal representing the divided voltage Av being less than the reference voltage signal. In one embodiment, the reference voltage signal is selected to be less than the DC bias voltage. In practice, the reference voltage is a load side voltage threshold, and in the exemplary embodiment, its magnitude correlates to an equivalent 40 Vrms load side voltage threshold. Therefore, the intersection detection circuit 220a interprets the corresponding load side voltage that is less than the reference voltage as “logic 0”, and interprets the load side voltage that exceeds the reference voltage as “logic 1”. Introducing a voltage threshold into the monitoring system 100 improves the reliability of open switch detection when electrical noise and line side voltage feedback paths exist.

  The intersection detection circuit 220b includes a pulse output unit 236b, and is configured to generate a corresponding pulse signal Bp based on the divided voltage signal Bv generated by the voltage divider 218b with respect to the reference voltage signal. The intersection detection circuit 220c includes a pulse output unit 236c, and is configured to generate a corresponding pulse signal Cp based on the divided voltage signal Cv generated by the voltage divider 218c with respect to the reference voltage signal.

  The peak detector 224a includes a peak output unit 240a, and is configured to generate the peak signal Ak in the peak output unit 240a in response to the pulse signal Ap generated by the intersection detection circuit 220a. The peak signal Ak is based on the peak value of the pulse signal Ap. Similarly, the peak detector 224b includes a peak output unit 240b and is configured to generate the peak signal Bk at the peak output unit 240b in response to the pulse signal Bp generated by the intersection detection circuit 220b. The peak detector 224c also includes a peak output unit 240c, and is configured to generate the peak signal Ck at the peak output unit 240c in response to the pulse signal Cp generated by the intersection detection circuit 220c.

  The logical AND circuit 228 is operably connected to the peak output units 240a, 240b, and 240c, and is configured to perform a logical AND operation on the peak signals Ak, Bk, and Ck generated by the peak detectors 224a, 224b, and 224c. The The logical AND circuit 228 includes an AND output unit 244 that transmits a closed circuit signal.

  The logical OR circuit 232 is operatively connected to each of the peak output units 240a, 240b, 240c, and is configured to perform a logical OR operation on the peak signals Ak, Bk, Ck generated by the peak detectors 224a, 224b, 224c. The The logical OR circuit 232 includes an OR output 248 that transmits an open circuit signal.

  FIG. 3 shows further details of an exemplary embodiment of the A phase branch of the monitoring unit 192. Referring to FIG. 3, the voltage divider 218a includes resistors R1 and R2 configured to generate a reduced line signal. Examples of nominal values for R1 and R2 are 1 MΩ and 2 kΩ, respectively. The reduced line signal is an AC signal that is about 0.2% of the line voltage transmitted by the line path 146a. The reduced line signal is superimposed on the DC voltage generated by the voltage source VDD to become a divided voltage signal Av. The voltage source VDD in the present exemplary embodiment is approximately 3.3V, which is applied to resistor R2 and a parallel connected capacitor C1 having a nominal value of 1033 pF. Therefore, the divided voltage signal Av is an AC signal that is DC biased by the magnitude of the voltage source VDD. The voltage divider 218a further includes a diode D1, which is a clamp diode configured to protect the monitor 192 from high voltage spikes.

  The divided voltage signal Av is AC-coupled to the intersection detection circuit 220a. In particular, a capacitor C2 having a nominal value of 0.1 μF is provided for AC coupling the divided voltage signal Av to the cross detection circuit 220a. Only the AC component of the divided voltage signal Av passes through the capacitor C2 as the connection signal Acup. Resistors R3 and R4 superimpose the concatenated signal Acouple on the DC bias voltage to form another voltage divider that forms a DC bias Abias signal similar to the divided voltage signal Av but DC biased by the DC bias voltage. To do. Resistors R3 and R4 define the magnitude of the DC bias voltage. In one embodiment, resistors R3 and R4 have nominal values of 287 kΩ and 100 kΩ, respectively, such that the DC bias voltage is about 0.85V. Therefore, the Abias signal is a sine wave signal that alternately exceeds or falls below the DC bias voltage. (See FIG. 4).

  Cross detection circuit 220a includes a comparator U1. The comparator U1 includes an inverting input (negative input), a non-inverting input (positive input), and an output that is the output of the crossing detection circuit 220a. The inverting input is configured to receive the Abias signal after passing through a series connected resistor R5 having a nominal value of 10 kΩ. A capacitor C3 having a nominal value of 33 pF is connected between the resistor R5 and the non-inverting input of the comparator U1 and is DC grounded.

  The non-inverting input of comparator U1 is coupled to resistors R6, R7, and R8. Resistor R6 has a nominal value of 318 kΩ and is further coupled to voltage source VDD. Resistor R7 has a nominal voltage of 100 kΩ and is connected to DC ground. Capacitor C4 has a nominal value of 330 pF and is connected in parallel with resistor R7. Resistor R8 is a feedback resistor having a nominal value of 1 MΩ in this example and is further coupled to the output of comparator U1.

  Resistors R6 and R7 define a DC reference voltage signal that is applied to the non-inverting input of comparator U1 and compared to the Abias signal. Thus, in the exemplary embodiment, the reference voltage signal is approximately 0.79V, which is less than the DC bias voltage of 0.85V.

  Comparator U1 includes a positive rail connected to voltage source VDD and a negative rail connected to DC ground. Capacitor C5 having a nominal value of 1 μF is connected to the positive rail and DC ground.

  The cross detection circuit 220a further includes a resistor R9 having a nominal value of 1 kΩ in this example and connected between the voltage source VDD and the output of the comparator U1, and a nominal value of 1000 pF and having the comparator U1. A capacitor C6 connected between the output and DC ground.

  The output of comparator U1 (ie, pulse signal Ap) is approximately zero (logic "" in response to the Abias signal (applied to the inverting input) being greater than the reference voltage signal (applied to the non-inverting input). 0 "). Also, in response to the Abias signal being smaller than the reference voltage signal, the output of the comparator U1 is a pulse whose magnitude is approximately equal to the voltage source VDD (logic “1”). The pulse signal Ap is input to the peak detector 224a.

  The peak detector 224a includes a diode D2, a resistor R10, and a capacitor C7. The diode D2 is connected between the capacitor C6 and the resistor R10 and is oriented to the anode of the diode D2 configured to receive the pulse signal Ap. Resistor R10 and capacitor C7 are connected in parallel between the cathode of diode D2 and DC ground. The voltage through the capacitor C7 is the output of the peak detector 224a, and the voltage level at which the capacitor C7 is charged represents the peak signal Ak.

  In response to receiving a pulse at the pulse output 236a for a period exceeding about 60 milliseconds, the capacitor C7 is charged to about 3.3 volts (the magnitude of the voltage source VDD) and the peak signal Ak is a logic "1" value. It becomes the voltage showing. The values of resistor R10 and capacitor C7 are selected to provide a discharge time constant that discharges capacitor C7 for a predetermined period when pulse signal Ap is absent. An example of the predetermined period is about 47 microseconds, and examples of the values of the resistor R10 and the capacitor C7 are 47.5 kΩ and 1 μF, respectively. Therefore, when the pulse signal Ap does not transmit a pulse longer than the approximate predetermined period, the capacitor C7 is gradually discharged, and the peak signal Ak becomes a value of substantially zero volts (logic “0”). The output of the peak detector 224 a is a peak signal Ak, which is supplied to the logical AND circuit 228 and the logical OR circuit 232.

  The B-phase branch and the C-phase branch of the monitoring unit 192 have substantially the same configuration as the above-described A-phase branch.

  The logical AND circuit 228 includes a three-input AND gate configured to receive each peak signal Ak, Bk, Ck. The AND gate 282 is configured to generate a logic output signal that assumes a logic “1” value only when each of the peak signals Ak, Bk, Ck is a logic “1” value. The logic “1” of the AND output 244 is a closed circuit signal, a line voltage has been detected in all three line paths 146 between the service switch 172 and the load 112, and the service switch 172 is closed. It shows that.

  The logical OR circuit 232 includes a three-input OR gate configured to receive each peak signal Ak, Bk, Ck. The OR gate 286 is configured to generate a logic output signal that assumes a logic “0” value only when each of the peak signals Ak, Bk, Ck is a logic “0” value. A logic “0” at OR output 248 is an open circuit signal indicating that there are no line voltages on all three line paths 146 between service switch 172 and load 112 and that service switch 172 is open. Show.

  Referring to FIG. 4, the three-phase signal continues to pass through the monitoring unit 192. As shown in FIG. 4, the DC bias signal graph 400 includes a DC bias signal that is an input (including an Abias signal) to the cross detection circuits 220a, 220b, and 220c, and a reference voltage signal that is a DC voltage having a certain magnitude. Indicates. The voltage on the left of the disconnect line 290 is an input to the intersection detection circuits 220a, 220b, 220c when the service switch 172 is in the closed configuration, and the voltage on the right of the disconnect line 290 is when the service switch is in the open configuration. Input to the intersection detection circuits 220a, 220b, and 220c. The DC bias signal is a sine wave signal that alternately exceeds or falls below the DC bias voltage.

  As shown in the pulse output graph 402, the pulse signals Ap, Bp, Cp take a logic “1” in response to the DC bias signal being less than the reference voltage signal, and the DC bias signal exceeds the reference voltage signal. In response to logic "0". For the A phase signal, the comparator U1 forms the pulse signal Ap by comparing the Abias signal with the reference voltage signal. Other pulse signals Bp and Cp are generated in substantially the same manner. At a time after the disconnect line 290, the pulse signals Ap, Bp, Cp remain at zero volts (logic “0”) in response to the DC bias voltage exceeding the reference voltage signal.

  Next, in the peak output graph 406, as long as the pulse output units 236a, 236b, and 236c transmit pulses having a regular flow, the charging effect of the pulse signals Ap, Bp, and Cp is obtained by converting the peak signals Ak, Bk, and Ck to logical “ 1 "is indicated. The peak signals Ak, Bk, Ck gradually decrease in magnitude in the “positive half cycle” of the corresponding DC bias signal, but remain at logic “1”. After the cutting line 290, the magnitudes of the peak signals Ak, Bk, and Ck decrease, and the peak signals Ak, Bk, and Ck transition from the logic “1” to the logic “0” on the transition line 294, respectively.

  The logic gate diagram shows AND output 244 and OR output 248 when service switch 172 is set to an open state and a closed state. The closed circuit signal is shown as logic “1” transmitted by AND output 244 to the left of transition line 294, indicating that line voltage has been detected (monitored) on all three line paths 146. It is confirmed that the service switch 172 is in the closed configuration. As is apparent from the logic “0” conveyed by AND output 244, a closed circuit signal is not generated to the right of transition line 294. The open circuit signal is shown as a logic “0” signal transmitted by the OR output 248 to the right of the transition line 294, which indicates that all three line paths 146 have no line voltage, and the service switch 172. Is in an open configuration or a power failure has occurred at the source 104. As is apparent from the logic “1” conveyed by the OR output 248, no open circuit signal is generated to the left of the transition line 294.

  The flowchart of FIG. 5 illustrates a method 500 for determining the status of the service switch 172 using the monitoring unit 192. In block 504, the interrupt causes the processing circuit 150 of the measurement unit 152 to execute a subroutine corresponding to the method 500 stored in the memory 180.

  In block 508, the measurement unit 152 determines whether the load 112 should be disconnected from the source 104. Therefore, the measurement unit 152 refers to specific data stored in the memory 180 in order to determine a desired connection state. In one embodiment, the measurement unit 152 uses a flag indicating a desired connection state stored in the memory 180. Usually, the source 104 transmits an electrical signal including data indicating a desired connection state to the measurement unit 152 (remotely or directly).

  Next, if the measurement unit 152 determines that the three-phase load 112 should be disconnected from the source 104, the measurement unit 152 monitors the monitoring unit 192 for the generation of an open circuit signal at the OR output 248 at block 510. Thus, it is determined whether or not the service switch 172 is open. If the measurement unit 152 detects an open circuit signal, the measurement unit 152 determines that the three-phase service switch is open and stops the method 500 until the next interrupt (block 504). However, when the measurement unit 152 detects a closed circuit signal, the measurement unit 152 determines that at least one phase of the three-phase service switch 172 is unnecessarily closed.

  In block 512, the measurement unit 152 transmits a disconnection signal to the service switch 172 in order to transition the service switch to the open state. Under normal operating conditions, service switch 172 is opened in response to receiving a disconnect signal, thereby electrically disconnecting load 112 from source 104.

  In block 516, the measurement unit 152 again monitors the three-phase monitoring unit 192 for the generation of the open circuit signal to determine whether the three-phase service switch 172 has successfully entered the open state. If the service switch 172 is operating properly, the measurement unit 152 detects an open circuit signal and determines that the service switch has successfully entered the open state. At this time, the measurement unit 152 determines that the next interrupt ( The method 500 stops until block 504). However, if the measurement unit 152 detects a closed circuit signal, the measurement unit 152 determines that the service switch 172 has not been successfully opened.

  In block 520, in response to detecting that the service switch 172 has not been opened, the measurement circuit 152 resends a disconnect signal to the service switch 172.

  At block 524, the measurement unit 152 checks whether the retransmitted disconnect signal has opened the service switch 172 by monitoring the open circuit signal generated by the monitoring unit 192. If an open circuit signal is detected, the measurement unit 152 determines that the retransmitted disconnect signal has opened the service switch 172, and the measurement unit stops the method 500 until the next interrupt (block 504). However, if a closed circuit signal is detected, the measurement unit 152 determines that the retransmitted disconnect signal did not open the service switch 172, and the measurement unit 152 opens the service switch as shown in block 528. A service disconnection signal indicating that the state has not been reached is generated.

  In one embodiment, the service disconnect signal generated at block 528 is an electronic signal that is transmitted to the source 104 or another device via the transceiver 184. In addition, the service disconnect signal may be a lighted portion of the display 188 that visually alerts the technician to potential problems. In another embodiment, the service disconnect signal is any other type of signal desirable to those skilled in the art.

  Referring back to block 508, if the monitoring unit 152 determines that the load 112 should not be disconnected from the source, the measurement unit confirms that the service switch 172 is closed, as shown in block 532.

  In block 532, the measurement unit 152 monitors the generation of a closed circuit signal at the AND output 244 to determine that the service switch 172 is in the closed state. If the measurement unit 152 detects a closed circuit signal, the measurement unit 152 stops the method 500 until the next interrupt (block 504). However, if the measurement unit 152 detects an open circuit signal, the measurement unit 152 determines that at least one phase of the three-phase service switch 172 is unnecessarily open.

  In block 536, the measurement unit 152 transmits a connection signal to the service switch 172 in order to close the service switch 172. Under normal operating conditions, the service switch 172 is closed in response to receiving the connection signal, thereby electrically connecting the load 112 to the source 104.

  In block 540, the measurement unit 152 uses the monitoring unit 192 again to determine whether the service switch 172 has successfully entered the closed state by checking the AND output 244 for the closed circuit signal. If the measurement unit 152 detects a closed circuit signal, the measurement unit 152 stops the method 500 until the next interrupt (block 504). However, when the measurement unit 152 detects an open circuit signal, the measurement unit 152 determines that the service switch 172 has not been closed.

  In block 544, in response to detecting that the service switch 172 has not been closed, the measurement circuit 152 resends a connection signal to the service switch 172.

  In block 548, the measurement unit 152 checks whether the retransmitted connection signal has closed the service switch 172. Similar to block 540, the measurement unit 152 checks the closed circuit signal transmitted by the AND output 244. If a closed circuit signal is detected, the measurement unit 152 determines that the retransmitted connection signal has closed the service switch 172, and the measurement unit stops the method 500 until the next interrupt (block 504). However, if an open circuit signal is detected, the measurement unit 152 determines that the retransmitted connection signal has not caused the service switch 172 to be closed, and the service switch 172 has not been closed, as shown in block 552. A service connection signal indicating that this is generated is generated.

  In one embodiment, the service connection signal generated at block 552 is an electronic signal transmitted to the source 104 or another device via the transceiver 184. In addition, the service connection signal may be in the form of a lighted portion of display 188 that visually alerts the technician to potential problems. In another embodiment, the service connection signal is any other type of signal desirable to those skilled in the art.

  The utility meter 124 monitors the digital output of only the two signal lines 244 and 248 from the monitoring unit 192, thereby enabling the measurement unit 152 to quickly and easily determine the state of the service switch 172. In addition, since the OR output 248 transmits an open circuit signal only when the service switch is open, and the AND output 244 transmits a closed circuit signal only when the service switch is closed, two independent output lines Reference numerals 244 and 248 enable the measurement unit 152 to finally determine the operating state of the service switch 172.

  Although the present disclosure has been described in detail in the foregoing description and drawings, it is to be considered as a case description and not of a limiting nature. Of course, only preferred embodiments are presented and all changes, modifications, and further applications within the spirit of the present disclosure should be protected.

Claims (13)

A device used for a utility meter,
Three circuit paths that connect the electrical energy source to the load, and
Operatively coupled to the three lines pathway, (i) closed in which the open state in which the three lines path open circuit is formed, the closed circuit (ii) the three line paths are formed A service switch that can be set to a state,
A monitoring unit operatively coupled to the three line paths between the load and the service switch, configured to detect the presence or absence of a voltage at the load, further comprising: (i) a voltage at the load And (ii) a monitoring unit configured to generate a closed circuit signal in response to detecting the presence of a voltage at the load;
Whether the closed circuit signal is detected in response to a determination that the load should be operatively connected to receive the closed circuit signal and the load should not be disconnected from the electrical energy source A measuring unit configured to determine whether or not
The monitoring unit is configured to generate the open circuit signal only when the three line paths are all open, and to generate the closed circuit signal only when the three line paths are all closed. Tei Ru apparatus. The apparatus of claim 1, comprising:
The monitoring unit is operatively coupled to each of the three line paths of the at least one line path, and is configured to detect the presence or absence of a voltage at the load for each of the three line paths; apparatus. The apparatus according to claim 1 or 2, comprising:
The apparatus includes: a first signal line configured to transmit the open circuit signal; and a second signal line configured to transmit the closed circuit signal. The apparatus according to claim 1, wherein the monitoring unit is
A first crossing detector operably connected to receive a first electrical signal corresponding to a first line voltage at the load;
A second crossing detector operatively connected to receive a second electrical signal corresponding to a second line voltage at the load;
A first peak detection circuit operatively connected to the first crossing detector and configured to generate a first peak signal based on an output signal of the first crossing detector;
A second peak detection circuit operatively connected to the second crossing detector and configured to generate a second peak signal based on an output signal of the second crossing detector;
A first operatively connected to the first and second peak detection circuits and configured to generate the open circuit signal in response to each of the first and second peak signals being less than a predetermined value. A device comprising a logic circuit. The apparatus according to claim 4, comprising:
The monitoring unit is further operably connected to a third crossing detector operably connected to receive a third electrical signal corresponding to a third line voltage at the load, and to the third crossing detector. And a third peak detection circuit configured to generate a third peak signal based on the output signal of the third crossing detector,
The first logic circuit is operatively connected to the third peak detection circuit, and the open circuit signal is responsive to each of the first, second, and third peak signals being less than the predetermined value. A device configured to generate The apparatus according to claim 4, comprising:
A first operably connected to the first and second peak detection circuits and configured to generate the closed circuit signal in response to each of the first and second peak signals being greater than or equal to the predetermined value. Further comprising two logic circuits,
The first logic circuit includes a logic OR circuit;
The apparatus wherein the second logic circuit comprises a logic AND circuit. The operation method of the utility meter,
Disconnecting the load from the electrical energy source by forming an open circuit in a three circuit path that connects the electrical energy source to the load by a service switch;
Connecting the load to the electrical energy source by forming a closed circuit in the three circuit paths by the service switch;
Detecting the presence or absence of a voltage in each of the three circuit paths;
Generating an open circuit signal in response to detecting the absence of a voltage in all three circuit paths;
Generating a closed circuit signal in response to detecting the presence of a voltage in all three circuit paths;
Determining whether the closed circuit signal has been generated in response to determining that the load should not be disconnected from the electrical energy source . The method of claim 7, further comprising:
Supplying the open circuit signal to a first signal line;
Supplying the closed circuit signal to a second signal line independent of the first signal line. The method according to claim 7 or 8, further comprising:
Sending a disconnection signal to the service switch by a measurement unit operably connected to the service switch;
Transmitting a connection signal to the service switch by the measuring unit;
Determining that the disconnect signal has caused the service switch to form the open circuit in the at least one line path by detecting the open circuit signal in the measurement unit;
Determining that the connection signal has caused the service switch to form the closed circuit in the at least one circuit path by detecting the closed circuit signal in the measurement unit. The method according to claim 9, further comprising: retransmitting the disconnection signal to the service switch when the measuring unit detects the closed circuit signal after transmitting the disconnection signal to the service switch;
Retransmitting the connection signal to the service switch if the measurement unit detects the open circuit signal after transmitting the connection signal to the service switch. The method according to claim 10, further comprising: generating a service disconnection signal in the measurement unit when the measurement unit detects the closed circuit signal after the retransmission of the disconnection signal;
Generating a service connection signal at the measurement unit when the measurement unit detects the open circuit signal after retransmitting the connection signal. The method according to any one of claims 7 to 11, further comprising: detecting a voltage crossing in a first electrical signal corresponding to a first line voltage at the load by a first crossing detector;
Detecting a voltage crossing in a second electrical signal corresponding to a second line voltage at the load by a second crossing detector;
Generating a first peak signal based on an output signal of the first cross detector by a first peak detector circuit operably connected to the first cross detector;
Generating a second peak signal based on an output signal of the second cross detector by a second peak detection circuit operably connected to the second cross detector;
Generating the open circuit signal by a first logic circuit operably connected to the first and second peak detection circuits if the first and second peak signals are less than a predetermined value;
Generating the closed circuit signal by a second logic circuit operably connected to the first and second peak detection circuits when the first and second peak signals are greater than or equal to the predetermined value; Method. The method of claim 12, further comprising generating the closed circuit signal at the output of a logical AND circuit of the first logic circuit;
Generating the open circuit signal at the output of a logical OR circuit of the second logic circuit.

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